Two stone saws, top, and an unfinished ink stone excavated at the Uruujitokyu ruins in Itoshima, Fukuoka Prefecture, southwestern Japan, are seen in this photo provided by Kokugakuin University visiting professor Yasuo Yanagida.

ITOSHIMA, Fukuoka -- The history of the written word in Japan may have to be revised by some 300-400 years after artifacts linked to making ink stones were recently dated to the mid- to late-Yayoi period.

The emergence of writing in Japan has been dated to about the third century, based on pottery from the period decorated with written characters. However, research by Kokugakuin University visiting professor Yasuo Yanagida has shown that ink stone manufacturing was likely underway in the second and first centuries B.C. in present-day Fukuoka and Saga prefectures in southwestern Japan. As making ink stones is presumed to be for writing, the finding suggests written characters were adopted in the country far earlier than had been presumed.

Yanagida re-examined stone artifacts from the second century B.C. Uruujitokyu ruins in Itoshima, Fukuoka Prefecture, Nakabaru ruins in Karatsu, in neighboring Saga Prefecture, and the first century B.C. Higashi Oda Mine ruins in the town of Chikuzen, Fukuoka Prefecture.

Among the artifacts are thin stones with fan-shaped ends, polished on one side and left rough on the other -- typical features of ink stones. However, the items appear to have been broken before they were finished. The artifacts also include unfinished stone files for making ink from the ink stones, and stone saws. The collection of items together led Yanagida to conclude the people in the area had been making ink stones.

Ink stones are thought to have first been made in China in the third century B.C., toward the end of the Warring States period, and flat, rectangular stones became widespread during the Western Han dynasty.

Many Yayoi period stones have been found in recent years, primarily in northern Kyushu where Fukuoka and Saga prefectures are now, but it was unknown whether they had been made in Japan. Furthermore, even the oldest of the artifacts dated to about the first century. Yanagida's findings put the start of ink stone manufacturing in Japan at least 100 years earlier than that, and in nearly the same period as the rectangular stones were being made in China.

"There is nothing to say but that the stones were used by Wajin (Yayoi period Japanese people)," Yanagida said of the artifacts he analyzed. "There was a demand for the written word, and that's why (the ink stones) were being made. I suspect (Japanese producers) copied Chinese stones and began making them domestically," he added.